In a large pot, over medium- high heat, put 2 tablespoons of the olive oil. When the oil is hot, add the garlic. Once the garlic is hot, add the clams and 1 cup of water. Cover, and simmer until the clams open, about 3 to 4 minutes. Remove the clams as they open, discarding any clams that dont open. Pass the cooking liquid through a strainer and reserve. Remove the clam meat from shells, and coarsely chop.

Meanwhile, in a soup pot, heat the remaining 1/4 cup of olive oil over medium heat. Add the onion, and cook until tender, about 5 minutes. Add the tomatoes, basil, red- pepper flakes, 1 cup of water, and the reserved clam- cooking liquid. Taste, and season with salt. Bring to a simmer, and cook until thickened, about 20 minutes.

Add the bread cubes. Simmer, breaking up the bread cubes with a whisk to make a thick soup. Remove the basil. Stir in the chopped clams, and finish with a drizzle of olive oil.